1. Field of the Invention
The embodiments discussed herein relate to a data communication system, a data communication apparatus, and a sensor apparatus.
2. Background of the Related Art
Single-wire bidirectional data communication may have a configuration of transmitting a command from a master side to a slave side through a single communication line and sending back a command response from the slave side to the master side.
Such a system configuration may be used for quality testing at the time of product shipment such as, for example, transmitting a command from a test device corresponding to a master side to a product corresponding to a slave side, and receiving, at the master side, a response sent back from the slave side to check the quality of the product.
As conventional single-wire bidirectional communication techniques, there are proposed, for example, a communication technique which uses A/D and D/A conversion (Japanese Laid-open Patent Publication No. 2011-55312), or a communication technique which fixes a logic level via time clocking (U.S. Pat. No. 5,210,846). In addition, there is proposed a technique in which a first device transmits a clock to a second device by switching between a first level and an intermediate level, and the second device transmits, to the first device, information as to whether or not to output a second level during a period of the intermediate level of the clock (Japanese Laid-open Patent Publication No. 2012-169746).
On the other hand, there is proposed, as a conventional technique corresponding to a slave side of bidirectional communication, a technique which measures a sensor output by gradually changing trimming data, for example, fixes and stores trimming data for setting the sensor output to a desired value, and adjusts the sensor output with the stored trimming data (Japanese Laid-open Patent Publication No. 2002-310735).
With the conventional single-wire bidirectional data communication system, it has been difficult to reduce the circuit scale. The circuit scale turns out to increase due to, for example, a built-in A/D and D/A converter according to the aforementioned Japanese Laid-open Patent Publication No. 2011-55312, or addition of a timer circuit or the like for time clocking according to the U.S. Pat. No. 5,210,846.
As thus described, there has been a defect that, when realizing bidirectional communication conventionally such as writing data from the master side to the slave side or reading slave-side data from the master side, communication apparatuses at the master side and the slave side have a complicated circuit configuration, resulting in an increased circuit scale.